[time-nuts] SR620 on eBay
mikes at flatsurface.com
Wed May 4 21:33:48 EDT 2005
At 07:41 PM 5/4/2005, Brooke Clarke wrote...
>It's just a guess (my counter's tied up now so can't do experiment), but in order to get down to 1 micro hertz (1 pico second) there's some analog stuff (time to amplitude) going on and the manual says you should run the self calibration once per month.
Good guess. The SR630 does a T/A, followed by an A/D to achieve it's resolution.
I found a good (good = I can understand enough of it to make it useful) paper discussing various methods used to measure TI in the picosecond range. It mentions the SR620, and also covers the method used by the HP 5370, amongst others.
"Review of methods for time interval measurements with picosecond resolution." - http://elka.wel.wat.edu.pl/~ztc/met4_1_004.pdf
The paper references a PCI board with 200 ps single shot resolution (the author designed the card). Anyone used one of these, or know how much they cost? (Vigo T-2200 - http://www.vigo.com.pl/index.php?vigo=131 )
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